Fuel waste and generation of pollutants are problems experienced in present day automobile internal combustion engines as a result of the conventional choke mechanism, which is a fuel enriching device used to start a cold engine. The choke apparatus is either manually operated from a dashboard control or is thermostatically operated in response to the temperature of the engine via throttle linkages or electronic spray nozzle injectors.
In every instance these systems put raw fuel into the intake manifold of the cold engine and, while these devices serve the purpose of starting a cold engine, they cause excessive fuel waste and resulting high emissions that pollute the atomosphere as well as cause excessive engine wear. It is known that approximately 25 to 30% of the emissions produced during a so-called CVS "cold start" EPA emission test result from the operation of the choke apparatus.
The reason for this is that in an internal combustion engine system vacuum and air flow are at their lowest during engine startup. The gasoline and air are both generally cold and this makes it virtually impossible to produce a volatile and highly combustible atomized, efficiently mixed, air-fuel mixture during the engine startup cycle. Even when raw fuel is atomized into the engine with fuel injectors there is poor mixing of the fuel with the available air supply and this results in the very rich burn which causes air pollution and significant energy waste in starting present engine systems.
The injection type choke in conventional use is superior to the conventional carburetor type choke but the injection type system uses raw fuel and requires a high presure fuel pump employing a complex drive system to operate the injector valve and is still far from an efficient system. It can only spray raw fuel into the intake manifold or combustion chambers and efficient mixing with the available air supply is virtually impossible. With either the carburetion or injection type choking system, a major portion of the fuel condenses in the intake manifold and on the walls of the combustion chambers rather than mixing with the available air supply whereupon the condensed, unmixed fuel contributes virtually no engine startup energy, and furthermore converts to carbon and enriches the engine exhaust with significant amounts of carbon monoxide.
Thus, even the relatively high degree of atomization realized with the conventional cold start injector, which sprays straight fuel, does not provide the complete air mixing necessary for good combustion and does not significantly improve engine startup efficiency.
A further problem experienced with conventional enriching devices, where improper air-fuel mixing takes place, is the pronounced cooling effect which can lead to ice clogging of the carburetor when the atmosphere is cold and humid. Further, automatic chokes often stick or stay on longer than necessary causing undue fuel waste and air pollution. Hand operated chokes are especially troublesome because operators forget to move them to the off position when their operation is no longer needed.